Spiraling whitefly becoming a problem

December 5, 2012

A new insect that has made landfall on the island has no real predators, which is making it difficult to eliminate.

Stephen Brown, Lee County Extension Director and Horticulture Program leader agent, said the spiraling whitefly is easy to identify. He said it is a small insect that is no more than 1/8 of an inch to 1/4 of inch in size.

Jim Ryan, owner of Mango Tango Tropical's in St. James City, said it is called spiraling whitefly due to the pattern in which it lays its eggs. He said the eggs turn into nymphs and then crawlers, which is when they start moving around and start sucking the nutrition off the bottom of the leaves. When the crawlers turn into adults they head to a new location and the process begins all over again.

Article Photos

JIM RYANThis is the first stage of the rugose spiraling whitefly that individuals see – the laying of eggs, which in this picture was done on a coconut palm branch.

MEGHAN McCOYRugose spiraling whiteflies and their eggs found on a branch in St. James City.

The insects, which are essentially sap suckers, feed by sucking the sap out of the plant, which includes some of its favorites - coconut palm, gumbo limbo and black olive.

"They will leave a lot of black material on the plants that they affect," Brown said, which is called black sooty mold.

Rad Hazen, a retired palm grower on the island, said when the larva feeds it produces a sap that is very high in sugar content called honeydew. He said the black sooty mold is the fungus that feeds on the honeydew.

"The tree starts getting a dark mold on the leaves as a result to the sugars the white flies are putting out," Hazen said. "The leaves falling and sugars falling, makes the area of the tree sticky and the trees turn black."

In order to get rid of the black sooty mold, Hazen said you first have to get rid of the spiraling whiteflies.

"This thing really got to be a problem on Pine Island two years ago," Brown said.

Although Bonita Beach, Naples and part of Fort Myers have had cases of spiraling whiteflies, Brown said the epicenter on this coast is Pine Island, Sanibel and Captiva.

"It started on the east coast in places like Miami and Broward County," he said. "The problem is not as bad as last year. There might be some natural control coming up in the future. We hope it will come in pretty fast."

Hazen said the spiraling whiteflies have mostly been found on the north end of Pine Island and are slowly spreading to other areas of the island. He first began noticing them in the spring and summer.

Individuals with gumbo limbo and palm trees, and especially coconut palms, are going to have this bug in great numbers, Hazen said.

Jim said he started noticing the spiraling whiteflies early this spring. He said they have been real heavy on coconut and Christmas palms.

"We have had whiteflies forever, but not this type of whitefly," he said.

Brown said since the spiraling whitefly does not have any natural enemies, they have exploded in population, which has become the problem.

"What often happens, three, four or five years go by, our local predators catch on to this great new food source," Hazen said, which will hopefully knock numbers of the whiteflies down.

Unfortunately, Brown said, there is not much one can do from keeping the whitefly from multiplying.

"Protect your plants," Brown said, which can be done by using the best systemic insecticide that goes directly into the plant.

Michael Ryan, president of Tempco, said they utilize a root injection method that enters into the tree and is absorbed naturally.

"Once the treatment flows into the leaves, the insects eat the poison and die," he said. "The treatment doesn't compromise the tree. It's kind of like giving the tree an antibiotic to fight off a nasty bug."

Michael said their goal is to be as environmentally friendly as they can when determining the case-by-case treatments.

Hazen said he has found that the spiraling whitefly is very resistant to most insecticides. He said a good treatment for palm trees, although it is rather expensive, is to inject Safari into the trunk because the systemic insecticide stays in the tree and the whiteflies feed on the tree and it kills them.

The Arbor Jet System, which is another systemic insecticide, Hazen has found to work.

Michael said the Arbor Jet method is used by drilling into the tree to control the infestation.

Hazen said most of the growers on the island cannot afford the most effective treatments, due to the large quantity of trees they have on their property, which leaves them to fighting the spiraling whiteflies with soap.

"We cannot as an island start spraying broad-based insecticides," Jim said because it will kill off the predator wasps. "They will hatch out and take care of the problem."

He said the best way he has found to control the spiraling whiteflies is to use insecticidal soap and oil.

The formula Jim uses is one tablespoon of soap per gallon of water and two ounces of oil per gallon of water. He said individuals could use either soap or oil or a combination of both.

"You should still cover up and wear a mask for sure," Jim said when spraying.

He said to make sure and spray the infected area of the leaf, which is easy to located due to an abundance of white, waxy material found on the underside of the leaves, which is its eggs. He said make sure to spray enough of the formula to where it drips off the leaf in order to smother the eggs and nymphs.

The next day, he said use a garden hose with its strongest spray to target the area that was treated the previous day.

"Blast the remainder off the leaf," Jim said.

The procedure, he said, should be kept up to get rid of the problem. Jim said they suggest 10 days, if not a strong solution you can do it once a week.

"If everybody would fight this thing we would have a better chance of getting it under control," Hazen said.

He encourages individuals to share with their neighbors of what works.

"Hopefully we will find some predators, natural, or introduce a predator that will be effective in controlling it," Hazen said.